I have a guess: that it came from people saying something like, "The flint strikes the frizzle 'n then the gun fires."

This gun actually WAS a vital piece of equipment in its time. Here's a quote from the site's home page. The Northwest Territory Alliance (NWTA) is an American Revolutionary War reeanctment organization located in the American Midwest. We have over five hundred members from states as far west as Iowa, east to Ohio, north to the Canadian border and south to Tennessee.

The NWTA is a non-profit educational organization that studies and recreates the culture, lifestyle, and arts of the time of the American Revolution, 1775-1783. We strive to duplicate the uniforms, weapons, battlefield tactics and camp life of the era as accurately as possible.

Re-enactments...hey, CK, you-all got any flintlocks over there?